Use of a non-contacting sensor to measure the angular position of a steering column shaft or other types of rotating shafts/structures presents various challenges. Such challenges include, for example, circumstances requiring mounting of the shaft via a through-hole mounting arrangement, and/or the need to measure absolute angular position across multiple revolutions of the shaft.
The nature of non-contacting sensing, be it through the use of a Hall device, a magneto-resistive (MR) device, an inductive device, or other types of non-contacting sensor technologies, presents difficulties in properly positioning/mounting the sensor device relative to the rotating shaft. Prior sensor designs have positioned the sensor device at the end of the rotating shaft, generally in line with the rotational axis, to thereby measure angular position of the shaft via an “on-axis” sensing arrangement. However, in applications requiring through-hole mounting of the shaft, difficulties arise when attempting to position the sensor device at the end of the shaft in an on-axis sensing arrangement. Therefore, the sensor device is sometimes positioned at a location offset from the shaft and the rotational axis to measure angular position of the shaft via an “off-axis” sensing arrangement. Although somewhat cumbersome, an off-axis sensing arrangement may be used to measure the angular position of the shaft across one revolution of the shaft (i.e., across 360°). However, difficulties arise in applications requiring an off-axis sensing arrangement where measurement of angular position across greater than 360° (i.e., across greater than one full revolution of the shaft) is necessary, often requiring complex mechanical parts and/or additional electronics (i.e., more than one magnetic sensor device). In the specific case of a steering column shaft, measurement of angular position across 1800° (i.e., five revolutions) may be required.
Thus, there is a general need in the industry to provide an improved magnetic position sensor assembly for measurement of the rotational angular position of a rotating shaft. The present invention satisfies this need and provides other benefits and advantages in a novel and unobvious manner.